John Gill Commentary Psalms 74:18

"Remember this, that the enemy hath reproached, O Jehovah, And that a foolish people hath blasphemed thy name." — Psalms 74:18 (ASV)

Remember this, that the enemy has reproached, O Lord
Or "has reproached the Lord", as the Septuagint version and others render it, and very rightly; though not so well the former part of the clause, which it renders, or rather paraphrases, thus: "remember this your creation", or "creature"; whereas it should be connected with what follows, the reproach of the Lord by the enemy; and it is a prayer of the church, that God would remember the enemy and his reproaches, which seemed to be forgotten, and inflict deserved punishments on him, which will be done in due time, (Revelation 16:19) (Revelation 18:5Revelation 18:6) , and that

the foolish people have blasphemed your name ;
The "foolish people" are not such as want common sense, or are idiots; the blasphemers of God and Christ, and the blessed Spirit, are generally the wise and prudent of this world, from whom the things of the Gospel are hidden; but wicked and profane men. Scoffers at religion, and blasphemers of Christ, his truths and ordinances, are commonly such who walk after their own ungodly lusts, who, though wise to do evil, are foolish in matters of religion.

Perhaps the Gentiles, who do not know God, are meant here, and are so called (Deuteronomy 32:21). It is notable that the Papists bear the name of Gentiles in (Revelation 11:2Revelation 11:18), and may be the foolish people chiefly designed here, who worship images of gold, silver, brass, and wood, and are notorious for their blasphemies; (See Gill on Psalms 74:10).